Development Characteristics And Evaluation Of Hydrocarbon Source Rocks In The Zhifang Formation Of Erdos

The Zhifang Formation of Erdos basin is explored in a low level. In recent years, SO&G appears in the south of the basin. In order to evaluate the exploration potential of the Zhifang Formation, sedimentology, petroleum geology and organic geochemistry theory are applied and field section survey, core observation, organic carbon in the organic matter remains of mud rock, chloroform bitumen”A”, prolysis, kerogen carbon isotope in organic matter, kerogen microscopy,vitrinite relfectance, gas chromatograms of saturated hydrocarbons-chromaticness and other maturity indexes, comparative analysis on biological marker compounds in gas chromatograms of saturated hydrocarbons-chromaticness and other organic geochemical testing methods and technical routines are adopted, plus the division and comparison of Zhifang group stratum, lithologic analysis of Zhifang group, spatial distribution of dark madstone, analysis of the potential for oil and gas exploration and the oil sources comparisons, the following conclusion and cognition are also gained:The stratums of Zhifang Formation and underlie monk ditch are unconformable horizontally or conformable contacted, the Zhifang Formation is horizontally unconformable with the overlying long 10. The lithology of the Zhifang Formation is predominated by brownish red and celandine green gristone, gray conglomeratic sandstones and brownish red and purplish grey sandy mudstone in the north of the basin, where the granularity of the sands are relatively rough; while the south of the basin is predominated by grayish green and yellowish green fine sandstones and middle fine sandstone and fuchsia sandstone, where the granularity of the sandstones are relatively fine.The dark mudstones of the Zhifang Formation are developed in a relatively limited way, which mainly develop in the lower part of the upper section and the upper part of the lower section and are limited in south regions like Zhengning. Besides, it's featured by multiple layer sections, thin single layer, strong nonhomogeneity and common total thickness. Organic matters in the south region are richer, predominated by type II kerogen. It belongs to the middle mature stage; the organic matters abundance in the south reaches the standard of middle-fair source rock and that in the north reaches the standard of poor-non source rock. Certain differences exist on the biomarkers in the gas chromatography of dark mudstones between Chang-7, Chang-9 and Zhifang Formation, which can lay foundation for the research of the source of crude oil of the Zhifang Formation. Besides, it is thought that south crude oil mainly originates from hydrocarbon supply parent material of the Zhifang Formation; while the crude oil in the north and narrow north are from the mixed contribution of Chang-7 and Chang-9 and the latter predominates.